The present invention relates to the field of communications, and, more particularly, to phased array antennas and related methods.
Antenna systems are widely used in both ground based applications (e.g., cellular antennas) and airborne applications (e.g., airplane or satellite antennas). For example, so-called xe2x80x9csmartxe2x80x9d antenna systems, such as adaptive or phased array antennas, combine the outputs of multiple antenna elements with signal processing capabilities to transmit and/or receive communications signals (e.g., microwave signals, RF signals, etc.). As a result, such antenna systems can vary the transmission or reception pattern (i.e., xe2x80x9cbeam shapingxe2x80x9d or xe2x80x9cspoilingxe2x80x9d) or direction (i.e., xe2x80x9cbeam steeringxe2x80x9d) of the communications signals in response to the signal environment to improve performance characteristics.
A typical phased array antenna may include, for example, a central controller for processing the host commands and generating beam control commands (e.g., beam steering commands and/or beam spoiling commands) for the antenna elements based thereon. One or more element controllers may be used for controlling the antenna elements based upon the beam control commands. In larger phased array antennas, subarray controllers may also be connected between groups of element controllers and the central controller to aid in beam command processing and distribution, for example.
One problem that may become particularly acute in large phased array antennas is that of efficiently distributing the beam commands from the subarray controllers to the element controllers. This is partly due to the fact that some beam commands are particular to a given element controller (e.g., initialization commands, phase commands, attenuation commands, delay commands), while others may be intended for all of the element controllers (e.g., beam spoiling commands, operating frequency commands). Thus, some degree of individual element addressing is typically required. Yet, many of these commands generally require distribution to the element controllers in as close to real time as is possible. This problem may be further complicated by the fact that other data may also need to be communicated to and from the element controllers, such as temperature compensation data or telemetry data, for example.
Several prior art approaches exist for sending and receiving data to and from element controllers. For example, one such approach is to arrange the group of element controllers associated with each subarray controller into rows and columns, and individually address each of the element controllers to send data thereto. A disadvantage of this approach is that numerous sequential addressing commands must be used, for example, to sequentially address each of the element controllers in a group. Further, common data such as headers, etc., to be sent to all of the element controllers must be repeatedly sent to each of the element controllers, adding further delays.
One variation of this approach is to address an entire column of element controllers in a group and then sequentially address each element in the column. While this variation may provide some improvement, numerous sequential addressing commands and repeated sending of data may still be required.
Another prior art approach is to provide a dedicated data link from each subarray controller to each of its associated element controllers. By way of example, U.S. Pat. No. 5,353,031 to Rathi discloses an integrated module controller which, in one embodiment, is to have a respective data link for each of its associated antenna elements. In this embodiment, the module controller transmits data to all of its associated antenna elements in parallel. Yet, this approach simply may not be practical in large phased array antennas having numerous antenna elements, due to the wiring complexities that are likely to result.
A still further approach uses a respective multiplexed bus connected between each subarray controller and subgroups of associated element controllers. In such an approach, the element controllers will have addressing straps, for example, so that individual element controllers within each subgroup can be controlled to receive respective data. An example of this type of architecture is also disclosed in the above noted patent to Rathi, where in one embodiment a subgroup of row elements or column elements share a common multiplexed data bus with each element receiving respective control addressing signals. While this approach also has certain advantages, it may require high bus data rates, and it may also be cumbersome to implement address straps for large numbers of elements controllers.
In view of the foregoing background, it is therefore an object of the present invention to provide a phased array antenna with enhanced element controller data communication and related methods.
This and other objects, features, and advantages in accordance with the present invention are provided by a phased array antenna including a substrate and a plurality of phased array antenna elements carried by the substrate, and a plurality of element controllers connected to the phased array antenna elements. Each element controller may be switchable between inactive and active data receiving states. The phased array antenna may further include a plurality of subarray controllers and a plurality of data buses. Each data bus may connect a respective subarray controller to respective columns and rows of element controllers. Further, each subarray controller may cooperate with a respective data bus for sending data in parallel to a plurality of rows of element controllers and while sequentially switching a given column of element controllers from the inactive data receiving state to the active data receiving state. Accordingly, the phased array antenna according to the present invention provides enhanced element controller data communication while reducing the need for relatively high speed busses and complex addressing protocols, which may otherwise result in increased logic complexity, power consumption, and cost.
More particularly, each subarray controller may send data in parallel to all of the rows of element controllers and while sequentially switching a given column of element controllers from the inactive data receiving state to the active data receiving state. Each subarray controller may further switch a plurality of columns of element controllers (e.g., all of the columns of element controllers) to the active data receiving state to send common data thereto. By way of example, the common data may include at least one of beam shape data, temperature compensation data (e.g., temperature compensation index data), and operating frequency data.
Each subarray controller may provide clock signals to switch the columns of element controllers between inactive and active data receiving states. For example, the clock signals may be offset in time from one another to sequentially switch the columns. Also, respective clock signals may be substantially the same to activate a plurality of columns. A significant advantage of this method is that the common data and the individual data for each column can be efficiently intermixed on the same bus, using a common message header. Because a column of element controllers in the inactive data receiving state has no clock, it does not xe2x80x9cseexe2x80x9d the data being multiplexed, and this allows for a relatively simple design of the element controller receiver logic.
The data may include beam steering data, for example, and the plurality of element controllers may be a respective element controller connected to each of the phased array antenna elements. Furthermore, the phased array antenna may also include a central controller connected to the plurality of subarray controllers. Additionally, each subarray controller may send a telemetry request command to at least one column of element controllers, and each element controller in the at least one column may respond to the telemetry request command by sending requested telemetry data. A method aspect of the invention is for sending data between a subarray controller and a plurality of element controllers in a phased array antenna. Each element controller may be switchable between inactive and active data receiving states. The method may include sending the data in parallel from the subarray controller to a plurality of rows of the element controllers, and sequentially switching a given column of the element controllers from the inactive data receiving state to the active data receiving state while sending the data in parallel.